<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>inner</title>
</head>

<body>
    <div>hello</div>
    <script>
        window.onmessage = (e) => {
            console.log(e.data)
            e.source.postMessage(e.data, e.origin)
        }
    </script>
</body>

</html>